Accumulated Other Comprehensive Income (Loss) (Schedule Of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2013
Accumulated Other Comprehensive Income (Loss), before Tax		$ (57,412)		$ (57,412)			$ (86,690)
Deferred tax expense (benefit)		(22,536)		(22,536)			(33,709)
Accumulated other comprehensive income (loss), net of tax		(34,876)	$ (1,858)	(34,876)	$ (1,858)	$ (51,159)	(52,981)	$ 4,057	$ (25,268)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		1,632	(503)	1,327	(2,456)
Reclassification adjustment for losses included in income before income taxes		2,916	822	8,689	4,019
Unrealized Gains on Investment Securities Available for Sale
Accumulated Other Comprehensive Income (Loss), before Tax		26,926		26,926			8,343
Deferred tax expense (benefit)		10,298		10,298			3,245
Accumulated other comprehensive income (loss), net of tax	[1]	16,628	9,490	16,628	9,490	2,604	5,098	16,490	(10,091)
Income taxes		(2,094)		(4,145)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1]	3,470	0	6,692	0
Funded Status of Defined Benefit Plan
Accumulated Other Comprehensive Income (Loss), before Tax		(82,007)		(82,007)			(90,696)
Deferred tax expense (benefit)		(31,957)		(31,957)			(35,281)
Accumulated other comprehensive income (loss), net of tax	[1]	(50,050)	(8,287)	(50,050)	(8,287)	(51,888)	(55,415)	(8,790)	(10,743)
Income taxes		1,078	319	3,324	1,563
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1]	(1,838)	(503)	(5,365)	(2,456)
Employee Benefits, prior service costs		(53)	(53)	(158)	(158)
Reclassification adjustment for losses included in income before income taxes		(2,863)	(769)	(8,531)	(3,861)
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, before Tax		(2,916)	(822)	(8,689)	(4,019)
Unrealized Loss on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss), before Tax		(2,331)		(2,331)			(4,337)
Deferred tax expense (benefit)		(877)		(877)			(1,673)
Accumulated other comprehensive income (loss), net of tax	[1]	(1,454)	(3,061)	(1,454)	(3,061)	$ (1,875)	$ (2,664)	$ (3,643)	$ (4,434)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1]	$ 0	$ 0	$ 0	$ 0

[1] All amounts are net of tax.